from Ancient Greek*κατηχισμός(*katēkhismós, “katēkhismos”), from κατηχίζω(katēkhízō, “to catechize”), a later extended form of κατηχέω(katēkhéō, “to catechize, instruct, teach by word of mouth”), from κατά(katá, “down”) + ἠχέω(ēkhéō, “to sound, to resound”).